Pressure-induced multiple phase transformations of the BaBi3 superconductor

Abstract

Measurements of temperature-dependent resistance and magnetization under hydrostatic pressures up to 2.13 GPa are reported for single-crystalline, superconducting BaBi3. A temperature-pressure phase diagram is determined and the results suggest three different superconducting phases α, β, and γ in the studied pressure range. We further show that the occurrence of the three superconducting phases is intuitively linked to phase transitions at higher temperature, which are likely first order and structural in nature. With the α phase being the ambient-pressure tetragonal structure (P4/mmm), our first-principles calculations suggest the β phase has a cubic structure (Pm−3m) and the γ phase has a distorted tetragonal structure where the Bi atoms are moved out of the face-centered position. Finally, an analysis of the evolution of the superconducting upper critical field with pressure further confirms these transitions in the superconducting state and suggests a possible change of band structure or a Lifshitz transition near 1.54 GPa in γ phase. Given the large atomic numbers of both Ba and Bi, our results establish BaBi3 as a good candidate for the study of the interplay of structure with superconductivity in the presence of strong spin-orbit coupling.

Source-reported materials — not catalogue approval

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